Automatic vending machines are normally arranged so that deposited coins can be returned by actuating refund levers attached to the machines. When a user cancels the purchase of goods, paper money, coins, and the like deposited into the machines are returned. If the user operates the refund lever, a device inside the machine generates a refund signal within a coin sorter mounted in the automatic vending machine. A money returning signal is generated responsive to the mechanical novement of the coin sorter by utilizing the mechanism of the coin sorter. Each time the refund lever is operated the coin passage is opened to permit the return of the coin interlockingly lodged therein and a coin return signal is generated.
FIG. 1 illustrates a coin sorter of this type, wherein the coin passage is caused to be opened. As shown in FIG. 1, the coin sorter includes a fixed side wall 1 fitted with a movable wall 2 which is rotatable in the direction of an arrow by means of a spring 3. The movable wall 2 is shut by being pressed against the fixed side wall 1 to form a coin passage with the fixed side wall 1. The fixed side wall 1 is equipped with a rolling contact passage 5 on which coins deposited from a slot 4 roll, a sorting coil 6 for inspecting the properties of the coins rolling on the rolling contact passage 6, and a gate 9 capable of appearing in and disappearing from the position where the coins are dropped. The gate 9 is withdrawn from the coin passage when a deposited coin is judged to be genuine by the sorting coil 6. When the gate 9 is withdrawn, the coin is directed to a coin passage for genuine coins. The gate 9 is caused to project into the coin passage when a deposited coin is judged to be counterfeit by the sorting coil 6. In this event, the coin is directed to a refund passage 8. A refund lever 11 is made of metal and is rotatably supported by a pin 10 which acts as a shaft. A detection coil 12 is provided to detect movement of the refund lever 11. A roller 13 is fixed to the refund lever 11 and a projection 14 having a tilted surface is provided on the movable wall 2 in the direction opposite to the roller 13.
If the refund lever attached to the front surface of an automatic vending machine (not shown) is operated to separate the movable wall 2 from the fixed side wall 1, the refund lever will rotate clockwise around the pin 10. When the refund lever 11 is turned clockwise, the roller 13 runs on the tilted surface of the projection 14 on the movable wall 2 and thus the movable wall 2 separates from the fixed side wall 1, causing the coin passage to be opened. As above described, the clockwise rotation of the refund lever 11 makes part of the refund lever 11 enter the sensitive region of the detection coil 12 and this causes the output voltage of the detection coil 12 to change sharply to generate a refund signal characterized as a change of the output voltage. In a conventional coin sorter thus constructed, the problem is that there is a large number of parts becuase the detection coil 12 must be provided solely to generate the refund signal responsive to the turning of the refund lever 11.
A device intended to solve this problem is identified in the Japanese Official Patent Gazette No. 159288, 1980 under the title of "A Coin Sorter." FIGS. 2 and 3 are schematic diagrams of this device.
In FIG. 2, like reference characters designate like or similar parts in FIG. 1. Form example, there is shown a fixed side wall 1 and a movable side wall 2. The fixed side wall 1 and the movable side wall 2 are respectively equipped with opposiing coin sorting sensors 21, 21 corresponding to the sorting coil 6 in FIG. 1. In the coin sorting sensors 21, 21, two coils 22, 23 are connected in series. The coils 22, 23 are further connected to a capacitor 24 in parallel and, together with the capacitor 24 are connected to an oscillation circuit 25.
The oscillation circuit 25, when in standby state, is constructed to produce oscillations with resonant frequencies determined by the coils 22, 23 and the capacitor 24. If a genuine coin 26 passes between the coin sorting sensors 21, 21, the self-inductance of the coils 22, 23 will change, causing the oscillating frequency of the oscillation circuit 25 to change. In addition, since the spacing between the coin sorting sensors 21, 21 becomes awider if the movable wall 2 is separated form the fixed side wall by revolution of the refund lever 11 shown in FIG. 1, the mutual inductance of the coils 22, 23 will change, also causing the oscillating frequency of the oscillation circuit 25 to change. Accordingly, the changed oscillating frequency of the oscillation circuit 25 when the movable wall 2 is opened is stored as a second reference value in this device.
In this manner, a genuine coin signal and a refund signal can be obtained by distinguishing between a genuine coin being deposited and the refund lever being operated. This determination is made based upon whether the oscillating frequency of the oscillation circuit 25 conforms to the first or second reference value.
According to this device, two reference values must be set up, though the detection coil shown in FIG. 1 can be deleted. There is a disadvantage, however, because the coin sorters must be assembled and manufactured under strict quality control to prevent dimensional errors that affect the inductance of the coils 21. It is difficult to make the dimcnsions equal between both the walls 1, 2, when the movable wall 2 is shut against the fixed side wall 1 and exactly locating the coin sorting sensors 21, 21 for all coin sorters. The dimensions between the walls and the assembly conditions of the coin sorting sensors differ depending upon the individual coin sorter and, as a result, the aforementioned magnitudes of the first and second reference values also change depending on the individual coin sorter.
For this reason, the forst and second reference values for each coin sorter must be measured by depositing a genuine coin and operating the refund lever, respectively, in order to set values in a memory based upon the measured results. Accordingly, as the number of reference values increases, more time will be required to set the reference values. This in turn causes the device to be unnecessarily costly and difficult to adjust.